Ok, here is the terribad video of the priest.

Notice the priest starts in auto heal mode (druid gets shield and prom) then i mouse over the grid and immediately the priest stops. I demonstrate the dps keep going as I am mashing the dps macro. Once I move off of the grid then the priest starts to auto heal again.

My /stopcasting macro is two step

Step 1:
a. wow macro with nothing but /stopcasting
b. I disable my priests auto heal keymap

Step 2:
a. I enable the priest auto heal keymap

Let me know if you have any questions ... here is the vid link (don't laugh too hard)

http://www.youtube.com/watch?v=tWEUFnuIjoM